"Yes, coercive altruism is wrong. Indeed, it’s not even altruism,..." Mitchell says.
However, that's incorrect. Altruism is not about benevolence or generosity. Altruism is about duty, a duty imposed on us, a duty to give. Freedom to do one's duty is a contradiction in terms. There is no right not to do one's duty. The "haves" have a duty the "have nots," a duty to give, a duty to perform service. If one doesn't perform such duties voluntarily, then it's right to coerce such performances. If some have a duty to give to others, then those "others" have a right to take, whether by trickery, stealth or force.
The most consistent exponents of altruism are advocates of dictatorship: commies, Nazis, Moslem terrorists.